This invention relates to vibrating screen apparatus for separating different sizes of materials of generally the same type, such as crushed rock and gravel, and in particular to such apparatus which employ natural frequency principles to reduce the amount of energy required to operate the apparatus and which employ shaker motors to impart straight line vibration to horizontally-oriented screen sections.
The majority of known horizontal vibrating screens employ a "brute force" method of applying the vibration to the particular screen. That is, a motor turns a drive unit which includes geared shafts with eccentric weights. This unit is attached directly to the screen or directly to a basket holding the screen. These known vibrating screens have one mass, mounted to a base by means of one set of springs, with the screen basket being the mass. While this method is effective to cause vibration and effect separation of the various sizes of components as required, it requires the input of large amounts of energy. There is need in the market for a vibrating screen which can accomplish the same amount of work using more efficient drive mechanisms.
In the 1950s, Hewitt-Robins, Inc., of Stamford, Conn., introduced a line of vibrating screens it called its "hi-G" screens. These screens have two masses and two spring mountings, and are said to require much less energy to operate. However, due to various conditions, those screens were not widely commercially successful.
This invention relates to improvements over the above apparatus and to solutions to the problems raised thereby.